On January 31, the managers of Interstate Inc. seek to determine the cost of producing their product during January for product pricing and control purposes. The company can easily determine the costs of direct materials and direct labor used in January production, but many fixed indirect costs are not affected by the level of production activity and have not yet been incurred. The managers can reasonably estimate the overhead costs for the year based on the fixed indirect costs incurred in the past periods. Assume the managers decide to allocate an equal amount of these estimated costs to the products produced each month. Explain why this practice may not provide a reasonable estimate of product costs in January.